Dark Side of the Moon
by xtimepiratex
Summary: Upon meeting a mysterious man who calls himself "The Professor" and claims to know River Song, The Doctor has to face his past and return to the one place in time and space he thought he would never return to- the infested shadows of the Library.
1. Chapter 1: Darillium

Chapter 1

Darillium

The Doctor stepped out of the TARDIS. It was midnight on Darillium, so the park was closed. No tourists in the area. He could be alone. It had been some time since he was here last. That was the night he took River to see the Singing Towers. He was not as well dressed as he was that night. That night he made it a point to dress his best with a brand new tux. Now, he was wearing what came to be his usually garb after spending time in Victorian England: black trousers, lavender waist coat with pocket watch, light blue shirt, burgundy frock coat and of course his bow tie.

Off in the distance the Doctor could hear the Singing Towers. The Towers were not towers at all really, but two steep mountain peaks. They worked on the same principle as the theremin. The two mountains generated a strong magnetic field: one controlling volume and the other controlling pitch. The air currents circling the peaks disrupted the magnetic field creating various pitches at different volumes; literally the music of the wind. River had begged him for ages to go see and hear this wonder of the universe, but he was reluctant to do it because he knew that would be the last time they would be together; their last night before she went to The Library. Their relationship and subsequent marriage was a strange one by most standards; always meeting at different points in the other's time stream. The first time he saw her was the last time she saw him. A hazard of being wanders in the fourth dimension. He never truly said goodbye to her. He hates goodbyes. Always has; always will. That's why he never settled in one place. Always moving; always running; and never looking back. Except here.

Why did he come here? The Doctor was not one to take a trip down Memory Lane, but this time he wanted to reminisce. From where he was standing, next to the TARDIS in the middle of a clearing of indigo grass, the Doctor could see a walking path. The black stones that made up the path were dotted with diamonds, and the light from the lampposts reflecting off of them made it seem as if one were walking on a pathway of stars. It was the same path he and River took to the Singing Towers. As he walked over to one of the benches next to the path, he took a seat and looked down the path towards the Towers. He saw another bench beneath a silver tree; the one where he presented River with the sonic screwdriver he made for her. He remembered having her sit down; the glitter in her emerald evening dress catching the light from the lampposts; her smile as she opened the box. Inside the screwdriver was a neural relay that a younger version of himself would use to save River's data ghost to CAL, The Library's data core. She's alive, but not here. Not with him.

"You nostalgic idiot!"

The quiet was interrupted by a voice coming from behind the Doctor, in the direction of the TARDIS. He stood up and turned on his heels and saw a figure casually walking towards him.

"You have to love closed causal chains. You can't live with them and won't learn a thing without them."

"The park's closed," replied the Doctor. "Is it? Then why are you here?" retorted the stranger with a smile. His accent was close to neutral, but there was a hint of a British accent in his voice.

The stranger finally stepped into the light of the lampposts giving the Doctor a chance to see the one disturbing his time alone. The stranger appeared to be a young man in his mid-twenties. The hair on his head was a light brown and wavy and was combed off to the right and curled at the ends. His face was slightly narrow with blue-green eyes and sporting a goatee. The outfit he wore was a two button black suit with matching trousers, grey vest with a silver watch chain visible, a white shirt and black tie.

Flashing his psychic paper, the Doctor replied, "I'm the groundskeeper, and you're trespassing."

"Psychic paper," said the stranger reaching into his inside coat pocket and pulling out a brown leather business card holder, "a useful thing to have when trying to get into places uninvited, but you have to be careful to not let your mind wander. There's no telling what might show up on it, which is probably why you didn't let me get a good look at your, uh, 'credentials' Mr. Groundskeeper." As the young man put his psychic paper back into his coat pocket, The Doctor noticed a gold ring on his right ring finger inset with a large green gem.

"Well, so much for that. No, I'm not the groundskeeper. I'm the Doctor. Who are you?"

"Oh, have we finally reached that point in the conversation?"

"No, yes, well," the Doctor fumbling over his words, "we actually skipped that part of the conversation. That usually comes first. Except on Vende III. Conversations are always held in reverse, but never mind that! Who are you and what do you...wait." The Doctor paused. A look of realization was on his face. "A closed causal chain: a chain of events that causes itself forming a circle. We've met before haven't we?"

"Look, the old man's clever!" exclaimed the stranger, taking a step forward. "Yes, I've met you. An older you," He was now standing face-to-face with the Doctor, "but now it seems I'm going to have to work to earn your trust for once. For starters allow me to introduce myself. I'm the Professor." The Professor reached out to the Doctor to shake his hand.

"The Professor?" replied the Doctor. "Professor who?"

The Professor grinned mischievously, "Just Professor will do."

For once in his many lives, the Doctor was a little speechless! "That's new," he thought with a smirk.

"A pleasure," The Doctor reached out and took the Professor's hand and shook it, then pulled up the black sleeve of The Professor's coat revealing his vortex manipulator, "time agent."

The Professor gave a nervous grin, "Actually, I'm not a time agent. I'm just a time traveler, not much different from you."

The Doctor, skeptical, released the Professor's hand. The Professor took a step back, and after smoothing out the sleeve of his coat and adjusting his tie, he continued, "I'm just a time traveler like you, and nothing more. I come with a message for you, and it concerns your wife, River."

The Doctor's hearts stopped as the blood left his face, dozens of thoughts racing through his head: "How does he know River?! She's dead! What's he playing at?! Oh, god, The Library?! Something must be wrong with The Library!"

"Calm down, Doctor," reassured the Professor. "I bring good news…she's been _saved."_


	2. Chapter 2: She Has Been Saved

Chapter 2

She Has Been Saved

"What do you mean, 'she's been saved?!' Of course she's been saved! I saved her!"

"No, Doctor," answered the Professor, a little annoyed that the Time Lord did not catch his meaning. Walking up, he took his index finger and poked the Doctor's forehead a few times while saying, "Use that brilliant intellect of yours and listen to what I'm telling you! She has been _saved_."

The Doctor gave a blank stare as the wheels of his mind turned. Then it clicked!

"She's been _saved_!" he thought, as his trademark goofy grin started to appear. "She's been saved!" this time aloud.

"Yes, she's been saved!" exclaimed the Professor, wide-eyed and now sporting a goofy grin of his own.

The Doctor embraced the Professor and gave him a quick kiss on the cheek.

"Oh, you're brilliant," said the Doctor and then ran off to the TARDIS.

The Professor just stood there. No longer was he beaming with excitement. Instead, he had a blank look on his face. Adjusting his tie and regaining his composure, he said, "I know," with a smirk.

The sound of a door slamming shut echoed from the top of the hill. It was the TARDIS doors! The Professor turned his attention to the sound and with a horrified look on his face, the Professor shouted, "Doctor! Wait!" He bolted for the TARDIS and opened the door just as the engines started to turn over. As the Professor closed the door, he turned and saw the Doctor zipping around the TARDIS console pulling levers and flipping switches.

"Surely, you weren't planning on leaving without me?" huffed the Professor, irritation in his voice.

"By saving River's data ghost to the Library's data core, all of her physical attributes were saved as well. We should be able to use the planet's transmat system to bring her back," said the Doctor, seemingly oblivious to the Professor's question.

"Just like the survivors of the Vashta Nerada infestation," remarked the Professor.

"Exactly! Wait," the Doctor stopped fiddling with the console and gave the Professor a suspicious stare, "how you know about that?!"

"I'll leave you to figure that out," said the Professor with a sly smirk.

The cogs of the Doctor's mind began to turn again concerning the newest passenger onboard the TARDIS. "Who is he, and why is he here?" he mused. The Doctor continued setting the coordinates for the Library while keeping an eye on the Professor as he strolled around console room. He appeared to be comfortable in the magnificent time ship. No signs of the usual shock and awe associated with previous companions when they first start out. This was unnerving to the Doctor. "He's been here before," he thought.

"So do you think the Vashta Nerada will still be there?"

The Professor interrupted the Doctor's thoughts with his question. The Doctor really did not think about the Vashta Nerada still being in the Library.

"Perhaps," admitted the Doctor, uncertainty in his voice. If the Vashta Nerada were still in the Library, and they most likely were, it would make things difficult. Last time he was in the Library, he scared them into submission for a short time. This time it may not work; especially since he had been erasing himself from the history books.

Leaning on the console across from the Doctor, the Professor reassured him, "This little escapade should be quick: in and out. We go to the Library, find ourselves a transmat system, pull up River's data, and push the button. The Vashta Nerada won't even realize we're there."

"What's a Vashta Nerada?"

Both time travelers turned their attention to the source of the question. It was Clara Oswald, the Doctor's current traveling companion. She was standing at the entrance to the corridor at the bottom of the stairs as if she had just awoken. Clara had been recovering from her last adventure with the Doctor on Trenzalore where she saved his life. Her green and blue checkered dress and black leggings still had some dust from the graveyard planet on them.

"Clara, you don't need to be up and about!" exclaimed the Doctor. He rushed over to her and whipped out his sonic screwdriver. The buzz of the device could be heard as he used it to perform a quick scan, and with a flick of his wrist he stared into the emitter crystal to read her vitals.

"All vitals are good. No sign of any injury or trauma. How do you feel?" asked the Doctor, cradling her head in his hands and looking into her big brown eyes. Taking his hands and gently putting them down, Clara responded, "I'm fine Doctor. Now what's going on?" When she looked up into the Doctor's worried face, he started to smile. She had only been traveling with the Doctor for a short time, but it was a smile she had come to know very well. It meant that he was taking them on another adventure. The Doctor whirled around and leapt to the top of the stairs and as she followed him up to the console, he began to explain:

"_The_ Library, the 51st century. The largest one in the universe; so large, that it takes up an entire planet! Every book ever written is stored there. The core of the planet is the largest and most complicated hard drive of that period."

"That's where River is," said Clara as she followed him around the console.

"Yes, wait!" exclaimed the Doctor as he turned to address the brunette following him, "How did you know that?"

"She told me," she said tapping her temple. Clara had met River in the dream world just before Trenzalore. River stayed connected to her mind to give advice and help them save the Doctor's friends, and in the process, she learned about the Doctor's past with the archeologist.

The Doctor's eyes shifted back and forth as he processed her response. "Oh…Well, anyway, yes, that's where River's data ghost has been saved: The Library's data core. We're going to bring her back!"

"It will be nice to have your wife back, but how?"

"Are the two of you going to continue to walk about like you can't see me?!" said the Professor, who had been sulking at the Doctor and Clara's disregard for his presence or input. The Doctor turned to the Professor, took a deep breath and said, "Clara. The Professor." The Professor smiled and with a slight bow responded, "A pleasure to meet you Ms. Clara."

"Yeah. Likewise." Pulling the Doctor off to the side she whispered, "Ok, who is _he_?"

"Someone from my future," muttered the Doctor, who was still feeling a little uneasy about him.

"Can we trust him?" asked Clara.

"I can hear you, you know?"

They both turned around and saw the Professor with his hands in his trouser pockets looking dejected. He leaned on the console and said, "Look, Doctor, I know you just met me, but I'm a person you will come to trust someday." The Doctor was still unsure, but his new companion seemed earnest in his plea. That did not mean anything though. He has known many beings in the universe that can sell a lie convincingly, he included. The Professor could be no different.

"Doctor, please. You're going to need my help if you want to pull this off," said the Professor.

The Time Lord took another deep breath. "What the hell," he thought. "Alright, Professor, you suggested we do this, so you lead the way."

The Professor's face brightened on hearing those words. "Brilliant," he said with a grin, "Alright." He turned to the console and placed his hand on one of the leavers. Turning his head to face the Doctor and Clara, the Professor exclaimed, "Next stop: The Library!" and pulled the lever.

WHOOSH-WHOOSH-WHOOSH-WHOOSH-THUD

The Doctor grabbed the screen and began checking their time coordinates: The Library; late 51st century; about mid-day. They were in the right place in space-time, so that was good. The Professor was busy next to him making final checks before they stepped outside, and when The Professor finished, he rushed to the door. The Doctor flipped the final switch to put the TARDIS in park, and then joined Clara and the Professor at the door.

"Right, now," said the Professor, "we need to be fast. I tried to get us close to a transmat system for us to use. If we're clever and quick, the Vashta Nerada won't even know we're here. Count the shadows; don't let your shadow cross another; and stay out of the dark."

On hearing the Professor's words, Clara's face went pale.

"Alright, ready?" asked the Professor.

Clara nodded as did the Doctor.

The Professor smiled. "Here we go," he said, and he opened the door and stuck his head out. Before the Doctor and Clara could follow him out, the Professor came back in and closed the door. He turned around and looked at the Doctor and Clara with a puzzled look on his face.

"What is it?" asked Clara.

The Professor's expression remained unchanged as he said, "There are people outside…a lot of people."


	3. Chapter 3: The Library

Chapter 3

The Library

Clara stepped out of the TARDIS into a large open room. The floors were made of wooden panels, and there was a desk at the center of the vast room in two halves forming a circle with what she could only describe as an abstract statue in front of it. Behind the desk, she could see a woman who, she assumed to be the librarian if this was a library. As the Professor stated, there were several people in the room, fifteen or so not including themselves, but not what she would consider "a lot." A wooden orb was floating nearby, and appeared to have a camera lens. "A security camera," she thought. It turned in her direction as the blue recording light began to flash and then flew off. She turned her attention to the Doctor and the Professor who were standing in the middle of the room. As she walked towards them, she began to hear their conversation.

"Why are there people? The Library was suppose to be quarantined after I left," huffed the Doctor, taking a step forward with his hands on his hips, and then turning to face the Professor.

The Professor just stared off into the distance with the same confused look he had in the TARDIS. "I don't know," he said, "but that's a good question."

As Clara came to join them, the Professor walked off in the direction of the librarian's desk. The Doctor pulled out his sonic screwdriver and began scanning the ground as people walked past. As soon as he was done with one, he rushed to another.

"Doctor, what are you doing?" asked Clara.

"Scanning the shadows," replied the Time Lord as he stopped to check his readings, "for Vashta Nerada." The three people he scanned were not being stalked. That was promising, but not enough information. He checked his watch: late 51st century, mid-day. Those were the same space-time coordinates given on the TARDIS. "Where are they?" he thought aloud.

"So what's a Vashta Nerada?" Clara inquired arms crossed. "The Professor mentioned _shadows_?" The Professor's warning before stepping out of the TARDIS made her feel like a frightened child. Whatever a Vashta Nerada is, it could put the Doctor on high alert, and that was scary.

The Doctor continued going to and fro, scanning even the smallest shadows at the edge of the room. With Clara in tow, he began to explain, "Yes, they're microscopic organisms; predators that stalk their prey in swarms by mimicking the shadows of their victim."

Clara's eyes widened as she began to realize the meaning of the Professor's words. "So every shadow could be Vashta Nerada?!" she muttered while looking nervously at every shadow she could see including her own.

"Not every shadow," corrected the Doctor, putting away his sonic screwdriver, "but _any_ shadow."

"Doctor!"

The shout came from the Professor, who was now being scolded by the librarian for shouting in the Library. He appeared to apologize to her before motioning for the Doctor and Clara to meet him at the desk.

As they walked in his direction, Clara asked, "So who is he again?"

"Not sure," said the Doctor. "I don't really know him yet."

The Professor met them half way. "So did you find anything?" he asked the Doctor. The Doctor scowled as he shook his head slowly. "Something's wrong," he thought, "This place should be swarming with Vashta Nerada by now."

"Well, come with me," said the Professor motioning towards the desk, "I've got something to show you." They followed him up to the strange statue in front of the librarian's desk.

"It's a statue," remarked Clara.

The Professor turned to her and smiled. "Good observation, Ms. Clara," he responded, "but wrong."

Clara did not appreciate the snub remark. She turned to the Doctor for support, but he simply smirked. "Great," she thought, "now I have to deal with two of them."

The Professor reassured her, "It's alright, Ms. Clara. Only joking." He then turned and addressed the statue. "Locate River Song." The statue's head started to turn as he began to address his new friends. "At first, I thought that maybe the TARDIS' flight pattern may have gone wibbly-wobbly on us. It wouldn't be the first time, but…"

The statue's head had finished turning completely around, and to Clara's shock, it bore River's face! "River Song has left the Library. River Song has been saved," it said with River's voice!

The Professor took a deep breath as he looked at the Doctor. "She's still here," he muttered.

The Doctor stared into River's face as if he had not seen her in ages. "River," he murmured as he reached out to touch her cheek. "I'm so sorry."

"That's River's face!" exclaimed Clara.

"It's called a Node," explained the Professor. "They serve as interfaces with the Library's central computer. Their basic function is like the catalog system from the libraries of your time."

"But her face!" exclaimed Clara again, who was then shushed by the librarian.

The Professor sighed and continued explaining things to Clara. "Real flesh aspects. Humans of this century will sometimes donate their faces upon death to be used for such purposes. The Node picks a face from the central computer's database that the user will most likely find pleasing. The three of us were friends with River, so," he looked back at the Node which still bore River's likeness. The Professor crossed his arms and said to the Doctor, "If River is still here, then we're most likely in the correct time period. My vortex manipulator verifies that conclusion, as I'm sure your watch does. Also, the Library has reopened which means the Vashta Nerada have most likely been neutralized." He looked at the old Time Lord who was still gazing at River's face in the Node. "For once in our lives, Doctor," he said hopeful, "we may have just gotten a freebie."

The Doctor stood silent as his face slowly changed from sorrowful to stern. Taking one last look at the Node, he turned and started walking toward a set of double doors to the left of the desk. His bewildered companions followed.

"Doctor?" asked Clara trying to keep up with the Doctor's stride.

"We need a computer," he responded as he opened the doors.

"Excuse me!"

It was the librarian. She was standing behind her desk looking over her black rimmed glasses. "I need to see your library cards before you can access the Library's computer system." The Doctor and the Professor exchanged a single glanced and both pulled out their psychic paper as they returned to the desk. The librarian looked at the the two pieces of paper suspiciously, but accepted them as valid. "Dr. John Smith and Kevin Flynn," she said as she typed them into her registry. The Doctor arched his eyebrow at the Professor. His fellow time traveler simply shrugged as he put his psychic paper back in his inside coat pocket and began to leave. "And you too, Miss," she said to Clara.

"Oh! Uh," Clara stammered.

"Oh!" exclaimed the Professor who was half way to the door. He spun on his heels and said to Clara, "Sorry, Love, you dropped this on the way in, and I forgot to give it to you." With a wave of his hand, another piece of psychic paper appeared between his fingers. He handed it to the librarian who seemed unimpressed with his little trick. She gave it back to Clara and said, "Thank you, Ms. Oswin. Enjoy your visit to the Library." The trio then turned and headed toward the door.

The Doctor looked at the Professor as he opened the door. "Kevin Flynn?! _Tron_?!" he said.

"Hey! That was a brilliant film!" said the Professor defensively. "Don't knock it."

As Clara walked behind the two time travelers, she thought she saw something move along the wall to her right! Her heart stopped as she looked all around her; trying to deduce what it could have been. She looked up to her left and saw the security camera floating above her. The blue recording light flashed as it looked in her general direction and then moved off. "Just the camera," she thought with a sigh of relief.

"Come along, Clara!" cried the Doctor.

Taking a moment to compose herself, she started down the stairs to catch up with the Doctor and Professor at the bottom of the stairway.


End file.
